In underground mining, shearer loaders, which, in extraction operations, are used, in particular, for working coal, are moved along a conveyor that can be advanced in the face working direction and that comprises, in addition to guide rails for the shearer loader, a rack drive, which is usually constituted by toothed racks or a chain and into which racks or chain there engages from above the driving toothed wheel of a drive assembly of the shearer loader, which, by means of its machine body, reaches over the conveyor in the manner of a portal. The shearer loader can then be moved along the rack drive arrangement through motor-actuated driving of the driving toothed wheel. In order to ensure reliable engagement of the toothing of the driving toothed wheel in the rack drive constituted by the chain or the toothed racks, the drive assembly is guided on the rack drive by at least one guide element, or guide shoe. Owing to the great weight of the shearer loader, and owing to lumps of rock or the like, which can clog the rack drive arrangement, the wear, both on the driving toothed wheel of the shearer-loader drive assembly and on the guide shoe, is relatively high, and it is necessary for the guide shoes and/or the driving toothed wheel to be replaced at regular intervals.
In the case of a shearer-loader drive assembly known from DE 197 12 774 A1, the driving toothed wheel is screw-connected to a transmission toothed wheel. The toothed wheel can be demounted, following demounting of a cover that is opposite a housing baseplate of the drive assembly, together with a bearing tube and the bearings for the driving toothed wheel. The guide shoe comprises a specially designed hook projection, which engages both under and behind a lower guide strip of a toothed rack or the like. In the case of this solution, the resource requirement for mounting and refitting is relatively high, since, in the case of repair of the driving toothed wheel, it is necessary to demount a structural unit consisting of a driving toothed wheel, a transmission toothed wheel, bearings and a bearing shaft. The hook projection, which, by means of a V-shaped portion, engages under and behind the guide strip on the rack drive, is replaceably screw-connected to the housing baseplate.
There is known from the older, non-prepublished patent application DE 10 2006 032 680 of the applicant, a guide shoe, which, as a replacement part, can be detached relatively easily from the drive assembly, since, for the purpose of anchoring the guide shoe on the drive assembly, a robust bearing bolt is merely inserted in a bearing axle for the driving toothed wheel. The guide shoe has a base wall and an opposing wall, the bearing bolt engaging through these walls when in the mounted state. The guide shoe can be removed downwards from the drive assembly following demounting of the bearing bolt, while the drive assembly is still fastened to the machine body of the shearer loader. For the purpose of mounting/demounting the guide shoe, it is necessary only to remove a rack-drive bar.